Air turbine speed controlling device



Jufly 21, 1942. P. e. HOLT AIR TURBINE ,SPEED CONTROLLING nmvrcs FiledAug. 14, 1941 INVENTOR IHIIIHIIIIIIII ATTORNEY Patented July 21, 1942UNITED STATES PATENT OFFICE (Granted under the act of March'3, 1883, as

amended April 30, 1928; 370 0. G. 757) 4 Claims.

This invention relates to an air turbine speed controlling device andhas for an object to provide an air turbine whose air driven turbinewheels will rotate at a predetermined speed, which predetermined speedmay either be constant, in one form of the invention, or may be at apredetermined ratio to the speed of rotation of a shaft rotating underlow power from an outside source in another form of the invention.

A further object of this invention is to provide a means for controllingthe speed of an air driven turbine wheel, which means may be used invarious devices, one example of such use being a turn indicator foraircraft.

A further object of this invention is to provide an air turbine whosespeed will vary greatly with changes in the air supply to the turbine orwith changes in load on the turbine axis.

A further object of this invention is to provide a means for inicreasingthe power available from the low power control shaft without affectingthe speed of the shaft.

With the foregoing and other objects in view, the invention consists inthe construction, combination and arrangement of parts hereinafterdescribed and illustrated in the drawing, in which:

Fig. l is a partly sectional, partly elevational view of one form of theinvention in which the turbine wheel is driven at a constant speed; and

Fig. 2 is a similar view of another form of the invention in which thespeed of the turbine wheel is in constant or fixed ratio to the speed ofa low power shaft driven from an outside source of power.

Referring to the form of the invention shown in Fig. 1, there is shownat lo a turbine wheel having impeller blades driven by a jet of aircoming from nozzle I2 at the end of a pipe I 3 receiving air pressurefrom a suitable source, such as from a scoop mounted in'the air streamof an aircraft. The turbine wheel I8 is fixed on a shaft l4 journaled atIS in the turbine casing IS. A gear IT on the end shaft I4 is in meshwith a gear l8 on one end of another shaft 20, the other end of theshaft having a worm 3| mounted thereon. In mesh with the worm 2| is aworm gear 22 mounted on a, hollow drum 23. This hollow drum 23 has ashaft 24 journaled in a bearing 25 in the drum casing 26 and a gear 21at the end of the shaft 24 provides a power take-off therefrom. Axiallyaligned with shaft 24 is a second but hollow shaft 28 journaled throughthe bearing 33 in the drum casing 26.

hollow shaft 28 has its other end 33 anchored to a shaft 34. This shaft34 extends through the hollow shaft 28 and hollow drum 23 and is securedto or part of the half drum 35.

Fixed on the shaft 34 adjacent its other end is an escapement wheel 36within a housing 31. Likewise located within this housing 31 is anescapement fork 38 journaled on a shaft 40. Another journal shaft 4|within the housing 31 is provided with a balance wheel 42. Anchored atone end to the pivot shaft 4| of balance wheel 42 is a hairspring 43whose other end is secured to an anchoring pin 44 in the housing 31. Therate of rotation of the escapement wheel 36 is controlled in theconventional manner by the stiffness of the hairspring 43 on balancewheel 42 through the fork 38 with the usual rocker fingers 45 extendingto opposite sides of the escapement wheel pin 46 and the bifurcated forkfingers 41 cooperating with the escapement wheel teeth 48. As the hollowshaft 28 is rotated, the hairspring 3|, which in effect is like the mainspring of a watch, rotates the shaft 34 to thus rotate the half drum 35along with the hollow drum 23, the escapement wheel 38 and balance wheel42 keeping the rate of rotation of shaft 34 and a half drum 35substantially constant for, as well known in the use of escapements fortimepieces, the magnitude of the torque acting on the driving shaft 34has very little effect on the rate of the escapement so long as there issufficient torque to keep the escapement operating. The speed of theshaft 34 .is therefore limited by the rate of the escapement and as longas the turbine wheel l0 receives suflicient power to drive the hollowshaft 28 at a speed greater than the limiting speed of the shaft 34, atorque will be maintained by the main hairspring 3| on the shaft 34. Inorder to keep the speed of shaft 34 from becoming excessive the relativemotion of hollow shaft 28 and shaft 34 is used to control what is ineffect an air valve, this air valve including thehollow drum 23 to whichhollow shaft 28 is connected and the half drum 35 to which shaft 34 isconnected.

The air that has operated the turbine blades is conducted by a pipe 50from the turbine casing l6 through an opening 5| in the drum casing 26.The opening 5| in casing 26 leads to an inner circumferential groove 52within the drum casing 25. Opposite this groove 52 the hollow drum 23 isprovided with an opening 53,

' while the half drum 35 is provided with a correspondingly placedopening 54 which extends A hairspring 3| anchored at one end 32 to the55 through itscylindrical lip 55. Commencing at the lower edge of theopening 54, which is also the lower edge of the cylindrical lip 55, thehalf drum 35 is shaped like one-half of an hour-glass at 56, while theinterior of the hollow drum 23 is shaped like the other half of thehour-glass as at 51. Adjacent the outermost portion of the hour-glasssection 51, the hollow drum 23 is provided with a second opening 58leading to a space 60, while an opening 8| connects the space 60 to theatmosphere.

In operation, as the turbine wheel I!) is turned by the air pressurecoming through pipe I3, it rotates the worm 2| and thus the hollow drum23 with its hollow shaft 28 and, through main hairspring 3| and shaft 34it also rotates half drum 35. Escapement wheel 48 controls the rate ofrotation of shaft 34 and thus of half drum 35. As long as the air fromthe turbine casing I6 through pipe 55 and groove 52 may pass throughaligned holes 53 in hollow drum 23 and hole 54 in half drum 35, theturbine will be rotated at a constant speed. Should the speed of theturbine become excessive the hollow shaft 28 will tend to speed upfaster than the escapement allows shaft 3:! and half drum 35 to rotate,tending to twist main hairspring 3| as it does so.

Such displacement of the hollow drum 23 and half drum 35 relative toeach other starts to move their openings 53 and 54 out of alignment,thus, cutting down or cutting off the air that will escape thereto andfollow the arrows 52 and 83 to the atmosphere at 63. This creates a backpressure in groove 52 and thus through pipe 58 in turbine casing 18,slowing down the rotation of the turbine wheel l8, and diminishing thetorque on the hollow drum 23. With such diminished torque, the mainhairspring 3| acting on hollow shaft 28 tends to untwist and restore thehollow drum 23 to the position where holes 53 and 54 are againsufhciently aligned to keep the rotation of the hollow drum 23 inconstant balance with the rotation of the half drum 35 as permitted bythe escapement wheel 35. If the turbine tends to slow down for anyreason, the reverse action takes place, thus opening the valve bybringing holes 53 and 54 more nearly into alignment, allowing morepressure to leave the turbine, thus increasing its speed. With theturbine thus operating, power may be taken off gear wheel 27 which isrotating at a constant rate. r

If desired, power may also be taken off gear wheel 85 on shaft 28 whoserotation is likewise constant.

In the form of the invention shown in Fig. 2,

instead of using an escapement to control the air valve and thus controlthe rate at which the turbine wheel may turn, a rotating shaft is used,which shaft may be rotated at a very low power from an outside source,where the speed of such shaft must not be affected appreciably by anyadded mechanism. This outside low power shaft is shown at E8 having atone end a gear H connected to the outside power source, while its otherend is connected to a half drum [2 within a hollow drum [3 which in turnis within a drum casing M. The shaft 18 is journaled through a bearing'15 in drum casing 14 and a bearing 16 in hollow drum [3. The hollowdrum 13 is further journaled on an axially aligned stub shaft 15 in abearing H of drum casing '14. A gear E8 on the hollow drum 13 connectsthrough a gear train consisting of gear 88, shaft 8|, gear 82 meshingwith gear 83 on a turbine shaft 84. extending within the turbine casing85, to a turbine wheel therewithin. The air pressure for operating theturbine wheel with the casing 85 comes through pipe 88 from a suitablesource of air pressure to an interior circumferential groove 8'! in thedrum casing 14. The hollow drum [3 is provided with an opening 88opposite this groove so that the air may pass from the groove throughthe opening 88 and through an opening 90 in the half drum 12 to a secondopening 8| in the hollow drum 13. From the second opening 9| the airpasses through a second internal circumferential groove 92 through apipe 93 terminating in a nozzle 94 through the turbine casing 85 tooperate the turbine wheel therewithin.

An arm 95 on shaft 10, which may be spring mounted thereon if desired,tends to abut against a leg 96 on hollow drum 73 so long as drumopenings 90 and SI are in alignment permitting air to pass therethroughin the direction of the arrows 91 and 98 from the source of pressure airpipe 85 to the turbine air pipe 83. If desired, of course, arm 95 may bemounted in a manner to permit over-running in case the shaft 10 issuddenly stopped for any reason.

In operation of this form, air pressure from the source to the pipe 86passes freely through the hollow drum and half drum as long as the holesare aligned through pipe 93 to operate the turbine within the casing 85.Should the turbine shaft 34 have too much speed it will change therelative position of the hollow drum (3 to the half drum l2, bringingthe holes 98 and BI somewhat out of alignment, thus cutting down theamount of air pressure that passes through pipe 93 to the turbine andthus reduces the speed of the turbine until the holes are again aligned.If the turbine shaft speed becomes too slow, the holes would come intomore accurate alignment, permitting more pressure to thus increase theturbine speed.

Other modifications and changes in the number and arrangement of theparts may be made by those skilled in the art without departing from thenature of the invention, within the scope of what is hereinafterclaimed.

The invention described herein may be manufactured and used by or forthe Government of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

Having thus set forth and disclosed the nature of this invention, whatis claimed is:

1. An air turbine speed controlling device comprising in combinationwith an air turbine, an air conduit means through which the air pressurepasses for operating said turbine. means in said air conduit for varyingthe air flow to the air turbine inversely whenever the speed of theturbine varies from a predetermined constant, said means comprising anair valve including one rotatable valve element whose rate of rotationis directly controlled by the turbine and a second valve element, andmeans for controlling the rate of rotation of said second valve elementat a predetermined substantially constant te.

2. An air turbine speed controlling device comprising in combinationwith an air turbine, an air conduit means through which the air pressurepasses for operating said turbine, air valve means in said air conduitfor diminishing the air-flew to the air turbine when the rate ofrotation of the air turbine exceeds a predetermined substantiallyconstant rate, said air valve means including one rotatable valveelement whose rate of rotation is directly controlled by the turbine anda second valve element, and means for controlling the rate of rotationof said second valve element.

3. An air turbine speed controlling device comprising in combinationwith an air turbine, an air conduit means through which the air pressurepasses for operating said turbine, air valve means in said air conduitfor diminishing the air-flow to the air turbine when the rate ofrotation of the air turbine exceeds a predetermined substantiallyconstant rate, said air valve ineluding one rotatable valve elementwhose rate of rotation is directly controlled by the turbine and asecond valve element, and means for controlling the rate of rotation ofsaid second valve element, said second valve element rate controllingmeans including an escapement means.

4. An air turbine speed controlling device comprising in combinationwith an air turbine, an air conduit means through which the air pressurepasses for operating said turbine, air valve means in said air conduitfor diminishing the air-flow to the air turbine when the substantiallyconstant rate of rotation of the air turbine exceeds a predeterminedrate, said air valve including one rotatable valve element whose rate ofrotation is directly controlled by the turbine and a second valveelement, and means for controlling the rate of rotation of said secondvalve element, said second valve element controlling means including anoutside power means.

PLINY G. HOLT.

